Cold plate stability

ABSTRACT

A cold plate assembly includes a cold plate with at least two plumbing ports. The cold plate assembly further includes a spring plate assembly, which applies an actuation load to the cold plate. The spring plate assembly includes a spring plate and a spring pin moveable in a slot of the spring plate assembly to maintain the actuation load. The actuation load is configured to mechanically actuate the cold plate to a module.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/741,852 filed Apr. 30, 2007, the contents of which are incorporatedby reference herein in their entirety.

BACKGROUND

The present disclosure relates generally to integrated circuit heatdissipation devices, and, in particular, to methods and apparatuses forcold plate stability.

As high performance computers increase in performance, which may bemeasured in floating-point operations per second (FLOPS) or millions ofinstructions per second (MIPS), the associated microprocessors withinthe computers typically increase in both speed and required electricalpower. As manufacturers have sought to integrate multiplemicroprocessors or other components within a single package, such as amulti-chip module (MCM) or other multi-core technologies, the associatednumber of electrical connections for such packages has grown. In orderto reduce package size, many manufacturers have turned from pin gridarray (PGA) and ball grid array (BGA) interfaces to land grid array(LGA) interfaces. An LGA interface may use pads instead of pins or ballsto connect to a printed wire board (PWB) through a socket or similarinterface. LGAs may be preferred over PGAs or BGAs due to larger contactpoints and higher connection densities, allowing for higher clockfrequencies and more power contacts. However, since power consumed isdissipated as heat, LGAs may produce more heat than PGAs and BGAs ofcomparable size. With the combined challenges of more numerous andpowerful microprocessors in a given package, limits of air-cooling maybe exceeded as performance demands continue to increase. Moreover,traditional cold plate assemblies may not meet mechanical constraints ofmodern packages, particularly in a server environment where multiplepackages may be installed in a physically confined space.

Since it is desirable for performance and reliability to maintain amodule's active metallurgy at a specified temperature, advanced heattransfer structures and methods are needed to maintain both thermal andstructural stability.

SUMMARY

Embodiments of the invention include a cold plate assembly. The coldplate assembly includes a cold plate with at least two plumbing ports.The cold plate assembly further includes a spring plate assembly, whichapplies an actuation load to the cold plate. The spring plate assemblyincludes a spring plate and a spring pin moveable in a slot of thespring plate assembly to maintain the actuation load. The actuation loadis configured to mechanically actuate the cold plate to a module.

Additional embodiments include a cold plate assembly that includes acold plate with at least two plumbing ports and a spring plate assembly,which applies an actuation load to the cold plate. The cold plateincludes a top component coupled to a bottom component and cooling finsbrazed to at least one of the top component and the bottom component.The cooling fins provide a cooling fluid circulation path between theplumbing ports. The spring plate assembly includes at least one springplate, at least one spring pin, and an actuation screw, the actuationscrew adjustable to set the actuation load. The cold plate assemblyfurther includes at least one load arm, which locks the spring plateassembly onto the cold plate via the at least one spring pin of thespring plate assembly and maintains the actuation load.

Other apparatuses, and/or systems according to embodiments will be orbecome apparent to one with skill in the art upon review of thefollowing drawings and detailed description. It is intended that allsuch additional apparatuses and/or systems be included within thisdescription, be within the scope of the present invention, and beprotected by the accompanying claims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The subject matter which is regarded as the invention is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other objects, features, andadvantages of the invention are apparent from the following detaileddescription taken in conjunction with the accompanying drawings inwhich:

FIG. 1 is a perspective view of a node with multiple quadrants of coldplate assemblies that are plumbed together in accordance with exemplaryembodiments;

FIG. 2 is a perspective view of a quadrant of cold plate assemblies thatare plumbed together in accordance with exemplary embodiments;

FIG. 3 a is a perspective view of a cold plate assembly with load armsand a module subject to cooling in accordance with exemplaryembodiments;

FIG. 3 b is an exploded view of a cold plate assembly with load arms anda module subject to cooling in accordance with exemplary embodiments;

FIG. 4. includes a top view and side cross sectional views of thestructure of a cold plate assembly in accordance with exemplaryembodiments;

FIG. 5 is a top cross sectional view of the structure of a channel andmanifold for a cold plate assembly in accordance with exemplaryembodiments; and

FIG. 6 is a flow diagram describing a process for providing cold platestability in accordance with exemplary embodiments.

The detailed description explains the preferred embodiments of theinvention, together with advantages and features, by way of example withreference to the drawings.

DETAILED DESCRIPTION OF THE INVENTION

Disclosed herein are apparatuses and methods for cold plate stability.While there are a wide variety of electronic packaging and interfaceoptions, such as pin grid array (PGA), ball grid array (BGA), land gridarray (LGA), and hybrid LGA, a common issue exists in removing heatdissipated from modules utilizing these technologies. Greater modulesize, module density, and clock frequencies typically result in agreater production of heat. As a single module can contain multiplecomponents, such as a multi-chip module (MCM) or multi-core module ofmicroprocessors, memory, and the like, the heat dissipated from such amodule can be substantial. Moreover, an LGA module (interfacing via padconnections) or a hybrid LGA module (interfacing via pad and solderconnections) may require a large actuation load (e.g., about 60 gramsper electrical connection point) to maintain electrical continuitybetween the module and a printed wire board (PWB) through which themodule interfaces to other system components. In exemplary embodiments,the cold plate assembly disclosed herein provides both cooling and anactuation load for a variety of module designs, such as an LGA or hybridLGA module, through an enhanced stability structure that supports fluidcooling and interconnections to additional cold plate assemblies.

Turning now to FIG. 1, a perspective view of a node 100 with multiplequadrants of cold plate assemblies 200 that are plumbed together isdepicted in accordance with exemplary embodiments. In exemplaryembodiments, the node 100 is a processing assembly including processingsystem components such as memory modules, busses, and microprocessormodules affixed to a printed wire board (PWB) 102. The node 100 may be asubsystem of a larger system such as a mainframe computer. In exemplaryembodiments, the PWB 102 supports coupling modules, such as hybrid LGAmodules, to the PWB 102. The PWB 102 may support multiple or mixedpackaging and interfacing technologies. The node 100 may includemultiple quadrants of cold plate assemblies 200 for cooling multiplemodules. In exemplary embodiments, plumbing lines 104 route a coolingfluid, such as water, through each of the quadrants of cold plateassemblies 200, providing a cooling fluid circulation path though thenode 100. While the configuration of cold plate assemblies depicted inFIG. 1 includes four quadrants of cold plate assemblies 200, the scopeof the invention is not so limited. To the contrary, there may be anynumber of quadrants of cold plate assemblies 200, or alternate plumbingschemes between cold plate assemblies. Moreover, any number of coldplate assemblies may be used, including a single cold plate assembly.

Turning now to FIG. 2, a perspective view of a quadrant of cold plateassemblies 200 that are plumbed together in accordance with exemplaryembodiments is depicted. The quadrant of cold plate assemblies 200includes four cold plates 202 interconnected via plumbing lines 104. Aspring plate assembly 204 is depicted atop each of the cold plates 202.It will be understood by one skilled in the art that while one plumbingconfiguration is depicted in FIG. 2, many other configurations arepossible to source and return a cooling fluid to each of the cold plates202. In exemplary embodiments, the plumbing lines 104 are made primarilyof noncompliant (e.g., low flexibility) tubing to create a robuststructure that can be brazed together between the cold plates 202 toreduce the possibility of leaks. Plumbing the cold plates 202 togethermay facilitate cooling of multiple modules in a substantially planarfashion. Further details of the cold plates 202 and the spring plateassemblies 204 are provided herein.

Turning now to FIG. 3 a, a perspective view of a cold plate assembly 300is depicted in accordance with exemplary embodiments. In exemplaryembodiments, the cold plate assembly 300 includes a cold plate 202 and aspring plate assembly 204. The cold plate 202 includes a top component302 and a bottom component 304. A cooling fluid circulation path,described in greater detail herein, may run internally through the coldplate 202 between plumbing ports 306. In exemplary embodiments, the twoplumbing ports 306 are located at diagonally opposing corners of the topcomponent 302 of the cold plate 202, providing inlet and outlet pointsfor a cooling fluid to circulated through the cold plate 202. While twoplumbing ports 306 are depicted on the cold plate 202, multiple plumbingports 306 may be included in the cold plate 202 (e.g., multiple zones),providing inlet and outlet points on any surface of the cold plate 202.Moreover, the plumbing ports 306 may be located at any position relativeto each other, e.g., adjacent. To assist in alignment and placement ofthe components of the cold plate 202, a guide marker may be placed atone or more location on the cold plate 202, such as guide marker 308 onthe bottom component 304. In exemplary embodiments, the guide marker 308is located near a plumbing port 306 to aid in orienting the topcomponent relative 302 to the bottom component 304 when mating the topand bottom components 302 and 304. The guide marker 308 may be, forexample, a hole, a raised element, or a printed indicator.

In exemplary embodiments, the cold plate 202 is placed atop a module310, providing a heat transfer path to cool the module 310 for thermalstability of the module 310. The module 310 may include a variety ofelectronic components such as one or more microprocessors, memory,busses, and the like. In exemplary embodiments, the module 310 is amulti-chip module (MCM) with multiple chip subcomponents encapsulated ina single package. While the module 310 is depicted as a single package,it will be understood that the module 310 may also include multiplemechanical subcomponents which may be separable from the module 310,such as a lid, lateral supports, substrate material, and the like. Themodule 310 may utilize any packaging and interfacing technology known inthe art, such as a PGA, BGA, LGA, or hybrid LGA module. The module 310may make electrical contact with the PWB 102 via a socket 312. Althoughthe socket 312 obstructs a direct view of the module 310 in FIG. 3 a,the distinction between the socket 312 and the module 310 is apparent inFIG. 3 b. In exemplary embodiments, the socket 312 acts as an interfacebetween the module 310 and the PWB 102, and can vary in design based onthe module technology. For example, the socket 312 may include two-sidedspring or pad interfaces when the module 310 in an LGA, or one side ofthe socket 312 may include solder connections when the module 310 is ahybrid LGA. As the module 310 may require an actuation load to maintainelectrical connections, the cold plate assembly 300 may further includeone or more load arm 314 to hold the spring plate assembly 204 in placeabove the cold plate 202.

While the cold plate assembly 300 is depicted with two load arms 314, itwill be understood that any number of load arms 314 with a variety ofdesigns may be used within the scope of the invention (e.g., 1, 2, 4).For example, one or more of the load arms 314 could be designed as apost, a clip, or a hinge member. In exemplary embodiments, each load arm314 is coupled to a hinge plate 316. Each hinge plate 316 may beattached to the PWB 102 using any fastening method known in the art(e.g., through-hole fasteners). In exemplary embodiments, the couplingof the load arm 314 to the hinge plate 316 provides a pivot point suchthat the load arm 314 can pivot outwardly, thus simplifying placementand removal of the cold plate 202 and the spring plate assembly 204above the module 310.

In exemplary embodiments, the spring plate assembly 204 includes twospring plates 318 and an actuation screw 320. Actuation may be providedby fixed travel of the actuation screw 320 though the spring plates 318.While the exemplary spring plate assembly 204 includes a singleactuation screw 320 and two spring plates 318, it will be understoodthat the scope of the invention is not so limited. To the contrary,there may be multiple screws, or similar coupling means, and any numberof spring plates, laminated or otherwise, within embodiments of thepresent invention. For example, in applications that require anincreased actuation load, additional spring plates 318 can be added tothe spring plate assembly 204, while applications with a lower actuationload requirement may use a single spring plate 318. The spring plateassembly 204 may have vertical slots 322 at either end of the springplate assembly 204. The vertical slots 322 allow for adjustment andtravel of spring pins 324. The spring pins 324 may apply a force at eachend of the spring plates 318. In exemplary embodiments, each spring pin324 is located above an end of the spring plates 318, providing anattachment point for each load arm 314.

In exemplary embodiments, the module 310 is seated on the socket 312,the cold plate 202 is placed on top of the module 310, and the springplate assembly 204 is placed on top of the cold plate 202. An actuationload may be applied to the cold plate 202 via the spring plate assembly204. In exemplary embodiments, the actuation load is configured tomechanically actuate the cold plate 202 to the module 310. The load arms314 can be locked down onto the spring pins 324 of the spring plateassembly 204, thus maintaining the actuation load on the cold plate 202.The actuation screw 320 may be adjusted to increase or decrease theactuation load. Although a range of actuation load forces may beapplied, the actuation load force achieved through locking the springplate assembly 204 on the cold plate 202 may be about 200 to about 300lbs. The actuation load may be adjusted depending on the number ofconnections required between the module 310 and the socket 312. Forexample, if the module 310 is a hybrid LGA module, the requiredactuation load may be about 60 grams per electrical connection point. Inexemplary embodiments, the actuation load maintains a thermal interfacematerial gap thickness 326 of about 30 to about 50 microns between thebottom of the cold plate 202 and the top of the module 310. Moreover,the actuation load may be adjusted to account for varying heightdifferences between modules 310, as different modules 310 aremanufactured within a tolerance range, and the modules 310 may includechips or cores of varying heights. The actuation load may also beadjusted to account for additional forces imparted by plumbing lines,such as the plumbing lines 104 of FIG. 2, connected to the plumbingports 306 when multiple cold plate assemblies are plumbed together, asdepicted in the quadrant of cold plate assemblies 200 of FIG. 2.

Turning now to FIG. 3 b, an exploded view of the cold plate assembly 300is depicted in accordance with exemplary embodiments. FIG. 3 b providesan enhanced view of the cold plate 202 and the spring plate assembly 204separated and raised above the module 310, making the thermal interfacematerial gap thickness 326 more apparent. In exemplary embodiments, athermal interface material, such as thermal grease, is placed or appliedin the thermal interface material gap thickness 326, thus enhancing heattransfer between the cold plate 202 and the module 310. FIG. 3 b furtherdepicts the pivoting motion of the load arms 314 relative to the hingeplates 316, as the load arms 314 are pivoted outwardly to ease placementand removal of the cold plate 202 and the spring plate assembly 204 onthe module 310.

Turning now to FIG. 4, a top view and side cross sectional views of thestructure of the cold plate 202 and the spring plate assembly 204 aredepicted in accordance with exemplary embodiments. Sections A-A and B-Bprovide side cross-sectional views of the cold plate 202 and the springplate assembly 204. In section A-A of FIG. 4, a cooling fluid reservoir402 can be seen as gap between the top and bottom components 302 and 304of the cooling plate 202. In exemplary embodiments, the plumbing ports306 depicted in section A-A, are brazed to the bottom component 304 ofthe cold plate 202, providing structural stability while reducing therisk of leaks. The plumbing ports 306 may also be brazed or otherwisecoupled to the top component 302 of the cold plate 202. Section A-Afurther depicts other details previously described, such as thestructural relationship between components of the spring plate assembly204.

Section B-B of FIG. 4 depicts cooling fins 404 that run through thecooling fluid reservoir 402. In exemplary embodiments, the cooling fins404 are integral with the bottom component 304 of the cold plate 202, asdepicted in detail C. The dimensioning depicted on various views in FIG.4 is provided merely for purposes of example, and should not be viewedas limiting in scope, as the various components depicted can be scaledbased upon a particular application (e.g., various module sizes,actuation load requirements, cooling fluid flow requirements, and thelike). In exemplary embodiments, structural stability of the cold plate202 is achieved through brazing the cooling fins 404 to the topcomponent 302 of the cold plate 202. Brazing the cooling fins 404 mayenable the cold plate 202 to withstand a high actuation load associatedwith various module designs, such as a hybrid LGA (e.g., actuation loadof about 200 to about 300 lbs.), and thus providing cold platestability. Brazing the cooling fins 404 to the top component 302 of thecold plate 202 may further enable center point actuation, providing asubstantially uniform a thermal interface material gap thickness 326.Brazing the cooling fins 404 to the top component 302 of the cold plate202 may further contribute to a low deformation rate of the cold plate202 and the cold plate assembly 300, providing substantially uniformdeformation, and thus making coupling of multiple assemblies possible,such as the quadrant of cold plate assemblies 200 of FIGS. 1 and 2.Moreover, brazing may also provide enhance durability and resistance tocorrosive effects associated with long-term contact with a coolingfluid, such as water.

Turning now to FIG. 5, a top cross sectional view of the structure of achannel and manifold for a cold plate 202 is depicted in accordance withexemplary embodiments. Section D-D of FIG. 5 illustrates an exemplarycooling fluid circulation path 502 through the cooling fluid reservoir402 and the cooling fins 404. The cooling fluid reservoir 402 mayinclude all gap space in the bottom component 304 of the cooling plate202, not otherwise occupied by the cooling fins 404 or the plumbingports 306. In exemplary embodiments, the direction of flow and flow ratethrough the cooling fluid circulation path 502 can be adjusted byvarying the inlet and outlet pressure at the plumbing ports 306. Aspreviously described, the approximate location of the plumbing ports 306may be identified as the corner nearest to the guide markers 308.

Turing now to FIG. 6, a flow diagram describing a process 600 forproviding cold plate stability is depicted in accordance with exemplaryembodiments. For ease of explanation, the process 600 is described inreference to the cold plate assembly 300, with the cold plate 202 andspring plate assembly 204 as depicted in FIGS. 2-5; however, the process600 is not so limited to the depicted embodiments. In exemplaryembodiments, the cold plate 202 includes at least two plumbing ports306, providing an inlet and an outlet for a cooling fluid. The coldplate 202 may further include the top component 302 and the bottomcomponent 304. At block 602, the cold plate 202 includes cooling fins404 internal to the cold plate 202, the cooling fins 404 brazed forproviding internal stability for the cold plate 202. The cooling fins404 may be integral to the top or bottom component 302 and 304 of thecold plate 202, with brazing applied between the cooling fins 404 andthe non-integral component, e.g., the cooling fins 404 may be cast asfeatures of the bottom component 304 and brazed to the top component 302for enhanced internal structural stability of the cold plate 202. Inexemplary embodiments, the cooling fins 404 provide a cooling fluidcirculation path 502 between the at least two plumbing ports 306. Thecooling fluid reservoir 402 may also be part of the cooling fluidcirculation path through the bottom component 304 of the cold plate 202.

At block 604, the cold plate 202 is placed in contact with the module310. As previously described, the module 310 may utilize any packagingand interfacing technology known in the art, such as a PGA, BGA, LGA orhybrid LGA module. In exemplary embodiments, the module 310 interfaceswith the socket 312, which is positioned on the PWB 102. A thermalinterface material, such as thermal grease, may be applied to the top ofthe module 310 or the bottom of the cold plate 202 to enhance heattransfer through the thermal interface material gap thickness 326.

At block 606, an actuation load is applied to the cold plate 202 via thespring plate assembly 204. In exemplary embodiments, the spring plateassembly 204 includes at least one spring plate 318 and actuation screw320, the actuation screw 320 adjustable to set the actuation load. Theactuation load may also be influenced by the spring pins 324 and themovement of the spring pins 324 within the vertical slots 322. Inexemplary embodiments, the actuation load is centrally applied relativeto the cold plate 202 with internally brazed cooling fins, establishinga substantially uniform thermal interface material gap thickness 326.

At block 608, the spring plate assembly 204 is secured with at least oneload arm 314. In exemplary embodiments, the at least one load arm 314 issecured to the PWB 102 via a hinge plate 316. The secured spring plateassembly 204 translates the actuation load to the module 310 via thecold plate 202, providing external stability for the cold plate 202. Theprocess 600 may further include connecting a plumbing line 104 betweenone of the at least two plumbing ports 306 and a plumbing port 306 of asecond cold plate 202, forming an interconnected assembly, such as thatdepicted in the quadrant of cold plate assemblies 200 of FIG. 2.

Technical effects of exemplary embodiments of the invention may includeapplying an actuation load to maintain electrically connectivity to amodule, such as a hybrid LGA module, while providing fluid cooling.Further technical effects include support for multiple assembliesplumbed together, providing a scaleable solution for varying applicationscope. The use of brazing on internal cooling fins within a cold platemay provide substantially low and uniform deformation through enhancedstructural stability, while enabling the cold plate to withstand highactuation loads.

While the invention has been described with reference to exemplaryembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the appendedclaims. Moreover, the use of the terms first, second, etc. do not denoteany order or importance, but rather the terms first, second, etc. areused to distinguish one element from another. Furthermore, the use ofthe terms a, an, etc. do not denote a limitation of quantity, but ratherdenote the presence of at least one of the referenced item

1. A cold plate assembly, comprising: a cold plate with at least twoplumbing ports; and a spring plate assembly which applies an actuationload to the cold plate, the actuation load configured to mechanicallyactuate the cold plate to a module, the spring plate assembly comprisinga spring plate and a spring pin moveable in a slot of the spring plateassembly to maintain the actuation load.
 2. The cold plate assembly ofclaim 1 further comprising: at least one load arm which locks the springplate assembly onto the cold plate via coupling the at least one loadarm to the spring pin.
 3. The cold plate assembly of claim 1 wherein thecold plate includes cooling fins within the cold plate, the cooling finsproviding a cooling fluid circulation path between the at least twoplumbing ports.
 4. The cold plate assembly of claim 3 wherein the coldplate further comprises a top component and a bottom component.
 5. Thecold plate assembly of claim 4 wherein the cooling fins are brazed tothe top component.
 6. The cold plate assembly of claim 4 wherein thebottom component includes the cooling fins and a cooling fluidreservoir.
 7. The cold plate assembly of claim 1 wherein the springplate assembly includes a second spring plate and an actuation screw,the actuation screw adjustable to set the actuation load.
 8. The coldplate assembly of claim 2 wherein the at least one load arm is coupledto a hinge plate, the hinge plate providing a pivot point to pivot theat least one load arm to place and remove the cold plate and the springplate assembly in relation to the module.
 9. The cold plate assembly ofclaim 1 wherein a thermal interface material gap thickness isestablished between the cold plate and the module.
 10. A cold plateassembly comprising: a cold plate with at least two plumbing ports, thecold plate comprising: a top component coupled to a bottom component;and cooling fins brazed to at least one of the top component and thebottom component, wherein the cooling fins provide a cooling fluidcirculation path between the at least two plumbing ports; a spring plateassembly which applies an actuation load to the cold plate, the springplate assembly comprising at least one spring plate, at least one springpin, and an actuation screw, the actuation screw adjustable to set theactuation load; and at least one load arm which locks the spring plateassembly onto the cold plate via the at least one spring pin of thespring plate assembly and maintains the actuation load.